The invention relates to compressors/motors having one or more cylinders, an axial drive shaft, a canted swash plate carried by the shaft and connected to pistons mounted in the cylinders, the rotary movement of the shaft being translated by the swash plate into a reciprocal displacement of the pistons. Devices of this general character are variously referred to in the art as an axial plunger wobble pump, U.S. Pat. No. 3,663,122; wobbler drive mechanism, U.S. Pat. No. 2,513,083; crankless motion mechanism, Patent No. 3,069,913. See also U.S. Pat. No. 2,398,486.